A double-Π stub proximity feed U-slot patch antenna

The design and measured results of a rectangular U-slot patch antenna proximity fed by a double-Π stub feed are described. Using approximately 0.09λ of air gap separating the upper and lower dielectric, an impedance bandwidth of 26% centered at 4.4 GHz and a gain of 6 dBi have been achieved. The proposed antenna is noted to be tolerable to lateral displacement of the feed and produces a better impedance matching than the single Π-stub antenna. The radiation patterns obtained are stable across the passband.